this. I was literally at my LHBS buying fermcap for my wort starters just so i could boil in the 2000ml erlenmeyer. Then I realized #1, fermcap might not even prevent a boilover and #2 that I have an erlenmeyer because it has a flat bottom and easily works with a stir plate, NOT so I could boil in it.
Now I measure out the water in the erlenmeyer, pour into a pot, add DME, boil, transfer back to the e-meyer. done.